Sanitary pressure switch



Sept 15, 1970 c. w. LITTLE, JR S 3,529,106

SANITARY PRES SURE SWITCH l Filed Jam. 4, 1968 2i 6 54.

ev MJMJQWMMWW AT'TQRNEYS 3,529,106 SANITARY PRESSURE SWITCH Clarence W.Little, Jr., Brookfield, Wis., assignor, by mesne assignments, toWaukesha Foundry Company, Inc., a corporation of Wisconsin Filed Jan. 4,1968, Ser. No. 695,753 Int. Cl. H01h 35/40 U.S. Cl. 200-83 7 ClaimsABSTRACT OF THE DISCLOSURE Fluid is admitted under pressure to a tubereadily removable for cleaning or replacement. A portion of the tube isindented between a fixed boss and a boss mounted on a lever which issubject to adjustable spring pressure and which, when displaced bypressure within the tube, actuates the operating plunger of amicroswitch.

BACKGROUND OF INVENTION The instant invention was developed to meet aspecific demand in the food industries for a sanitary pressure switchthat would start and stop a pressurizing pump to hold a liquid foodproduct within a narrow range of pressures.

All presently available commercial switches require the provision ofextra operating parts exposed to the food and therefore necessitatingextra cleaning work. Moreover, they are relatively expensive. It isfurther true of some of the commercially available switches that theswitches themselves are exposed to contamination and to corrosion andare Aobjectionable from this standpoint.

While the instant switch has been developed for controlling pressure ofliquids, the invention is applicable wherever pressure response isdesired to be held within a predetermined range.

SUMMARY IOF THE INVENTION The instant device has solved all problems inthat itis simple and inexpensive and holds the fluid within anadequately narrow pressure range without exposing either the fluid orthe switch itself to any possibility of contamination, the fluid whicheffects the operation of the switch being confined within a tube whichrequires no special cleaning, either being a part of the food handlingapparatus and periodically cleaned therewith, or being discarded andreplaced from time to time.

The switch and pressure responsive apparatus are preferably connected.As disclosed, the connection is effected by a bracket which eithersupports the switch from the fluid-containing tube, or supports theactuating device from the switch.

In practice, the unitary assembly of bracket, switch operatingmechanism, and switch have been hung on a disposeable tube. The bracketcarries laterally spaced fulcrum pins with conical points engaged insockets of greater taper angle formed in the pressure-responsiveswitch-actuating lever. The bracket further includes an adjustablespring support for the bifurcated free end of the lever for theregulation of the pressure at which the lever will yield to operate theswitch.

Also mounted on the bracket is a tube-confining means through whichpasses the pressure tube upon which the assembly is suspended and withinwhich is confined the` fluid whose pressure is to be regulated. In thepreferred construction, the tube confining means comprises a chamberhaving a removable top to facilitate introduction and removal of thetube. The tube is compressed between a relatively fixed boss connectedwith the chamber top, and a relatively movable boss on the lever. Theseopposed 'United States Patent O ice 3,529,106 Patented Sept. 15, 1970BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view of an embodiment of theinvention taken in section on the line 1-1 of FIG. 2.

FIG. 2 is a view in side elevation of the device shown in FIG. 1.

DESCRIPTION OF ,PREFERRED EMBODIMENT A uid under pressure is confinedwithin the resiliently fiexible tube 6, which may be closed at one endor -may be an integral part of a fluid transporting system. The entireapparatus is preferably unitary and suspended on the tube.Alternatively, a base may be provided at 8 for the microswitch 10. Thisswitch is a conventional piece of equipment including a threaded stem 12through which the switch actuator 14 is reciproca-ble. Bracket 20 isadjustably positioned by the nuts 16 and 18 on the stem 12 to supportthe switch 10, or be supported thereby, as the case may be.

A lever fulcrum preferably comprises laterally spaced fulcrum studs orpins 22 which are desirably threadedly adjustable in the base 2.0. Thepins have conical points 24. Their positions are fixed by set screws 26.

The apices 24 of pins 22 are seated in conical sockets 2-8 of greaterangle, these being formed in the proximate surface of the switchoperating lever 30. Thereby the lever is pivotally operable withprecision.

The free end 32 of lever 30 is bifurcated to pass bolt 40 and issupported with adjustable bias by spring 34 on the bolt. A washer 36spanning the bifurcation of leVer 30 provides one seat for the spring.The washer 38 on bolt 40 is adjustably supported by nut 42 to provide anopposite seat for the spring. The bolt 40 is mounted in the wall 44 oftube confining means, here exemplified by a pressure chamber 50. Theposition of the bolt is adjustably fixed by a set screw 46. The pressureswitch is held to the bracket 20 by appropriate means such as the fiathead screws 48.

The resiliently fiexibly walled tube `6 extends through the tubeconfining means, where it is confined under pressure between opposingside walls and top wall 54 of the pressure chamber 50 and the lever 30which serves as the bottom thereof. Preferably, tube 6 is not onlydeformed by flattening but somewhat indented by engagement therewith ofat least one boss. Preferably there is a boss 52 on the removable topwall 54 of the pressure chamber and an opposing boss 56 which is carriedby the lever 30. The spacing between these bosses is less than theundeformed diameter of tube 6.,Wing nuts 58 on bolt `40 and 60 on bolt62 hold the top wall 54 to the.

chamber and permit ready removal thereof for the insertion orreplacement of the tube 6.

Variations of pressures to which the iiuid in the tube 6 is subject willtend to permit the lever 30` to rise or fall subject to the adjustablebias of spring 34. The tube 6 will normally be made of natural orsynthetic rubber or the like. However, even the relatively slightchanges in temperature to which such a tube may be subject may result inchanges of resilience in the wall of the tube, with resulting changes inthe range of response of the switch 10. It is found that by the use ofthe bosses 52 and 56 for the deformation of the tube by indentationthereof, the variations in response, otherwise attributable totemperature-induced variations in tube resilience at a given bias ofspring 34, can be minimized.

If the tube 6 is an integral part of the fluid handling aparatus,whatever that may be, it will be cleaned and sterilized by routineprocedures, together with the rest of such apparatus. If not, it stilldoes not require a separate cleaning operation because its cost is solow that the tube is disposable. It is only necessary to remove the topplate 54 to permit the tube 6 to be withdrawn, discarded, and replaced,if desired.

The balanced fulcrum provided by the adjustable pins 22 promotesaccuracy of response of the lever 30' and accuracy is further enhancedby the fact that the resiliently walled tube 6 is deformed between theopposing bosses 52 and 56, which have the effect of minimizing theresult of changes of temperature.

Contamination and dirt are preferably excluded from the vicinity of theswitch 10 by the use of a housing 64. The uid to be controlled beingpermanently enclosed in tube 6, no packing is required and no leakagecan occur to foul the switch.

The whole construction is extremely simple and inexpensive and hasoperated eifectively to hold within a narrow range the pressures towhich the fluid in tube 6 is subject.

Because it may be desired to use the switch for various purposes, andbecause the pumps and other equipment used in pressure control areconventional, no showing is required as to these, novelty beingpredicated upon the device illustrated.

What is claimed is:

1. The combination with a tube for fluid under pressure, of a brackethaving tube-confining means through which the tube extends and includingan opposed plate and lever having tube-deforming portions, means on thebracket providing a fulcrum for said lever, a spring biasing a portionof the lever toward said tube, means supporting the spring, and a switchmounted on the bracket and having actuating means engaged by the leverto be operated when the tube expands to oscillate the lever on saidfulcrum means against the bias of said spring, the tube-deformingportions of the plate and lever including at least one boss engaged withthe tube, the spacing between said plate and lever portions being lessthan the undeformed diameter of the tube, the tube being somewhatindended by said boss.

2. The combination with a tube for fluid under pressure, of a brackethaving tube-confining means through which the tube extends and includingan opposed plate and lever having tube-deforming portions, means on thebracket providing a fulcrum for said lever, a spring bias ing a portionof the lever toward said tube, means supporting the spring, and a switchmounted on the bracket and having actuating means engaged by the leverto be operated when the tube expands to oscillate the lever on saidfulcrum means against the bias of said spring, the tube-conining meanscomprising a pressure chamber having side wall portions with which sidesof the tube are engaged, said plate being removable to open saidcontining means to provide an opening through which the tube may beintroduced and withdrawn respecting said chamber.

3. A combination according to claim 2 in which said lever has a slottedfree end portion, the slot being spanned by a spring seat with whichsaid spring is engaged, a bolt connected with said chamber extendingthrough the slot and being provided with a second spring seat adjustablethereon and with which is engaged an end of the spring remote from thelever.

4. A combination according to claim 3 in which the switch has a threadedsleeve through which said switchactuating means is operable, saidbracket having an arm mounted on said sleeve, the fulcrum means for saidlever comprising pointed pins mounted on said arm in laterally spacedpositions, said lever having conically tapered sockets with which theextremities of said pins are en gaged.

5. A combination according to claim 4 in which the pins are threaded insaid bracket arm and individually adjustable therein.

6. The combination with a tube for fluid under pressure, of a brackethaving tube-conning means through which the tube extends and includingan opposed plate and lever having tube-deforming portions, means on thebracket providing a fulcrum for said lever, a spring biasing a portionof the lever toward said tube, means supporting the spring, and a switchmounted on the bracket and having actuating means engaged by the leverto be operated when the tube expands to oscillate the lever on saidfulcrum means against the bias of said spring, said switch having a stemin which its said actuating means is reciprocable, the said bracketbeing physically connected with the stem and having a portion projectinglaterally therefrom, the fulcrum means being mounted on the lateralyprojecting bracket portion and comprising transversely spaced studs withpointed ends, the lever having tapered sockets in which the pointed endsof said studs are engaged, said bracket carrying a pressure chamberconstituting said tube-conining means and having side Walls betweenwhich said tube extends and with which the sides of the tube are incontact, the said lever and top plate extending across said chamber atopposite sides thereof, the top plate and lever having opposing bosseswhich are convex toward the tube and engaged therewith in pressurecontact suicient to indent the tube.

7. A combination according to claim 6 in which means removably connectsthe top plate with the side walls of the chamber, said means including abolt extending through one of said side walls remote from said fulcrumstuds, the said lever being bifurcated to receive said bolt and the bolthaving a spring seat washer engaging the lever, the said spring beingseated against said Washer, the bolt having a second spring seat washerremote from said lever and with which said spring is also engaged.

References Cited UNITED STATES PATENTS 2,302,923v 11/ 19412 Zimarik.2,439,561 4'/ 1948 Cressey. 2,520,660 8/ 1950 Sedgwick. 2,740,858 4/1956 Euler. 2,742,544 4/ 1956i Lovick. 2,885,506 5/ 1959 Anderson.2,9923 02 7/ 196 1 Schuler.

ROBERT K. SCHAEFER, Primary Examiner J. R. SCOTT, Assistant Examiner

